WO2024024568A1 - Mélange d'électrode, électrode et batterie secondaire - Google Patents

Mélange d'électrode, électrode et batterie secondaire Download PDF

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Publication number
WO2024024568A1
WO2024024568A1 PCT/JP2023/026252 JP2023026252W WO2024024568A1 WO 2024024568 A1 WO2024024568 A1 WO 2024024568A1 JP 2023026252 W JP2023026252 W JP 2023026252W WO 2024024568 A1 WO2024024568 A1 WO 2024024568A1
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acid
electrode mixture
group
fluorine
electrode
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PCT/JP2023/026252
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English (en)
Japanese (ja)
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あきほ 小倉
穣輝 山崎
佑磨 市瀬
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ダイキン工業株式会社
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Publication of WO2024024568A1 publication Critical patent/WO2024024568A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to an electrode mixture, an electrode, and a secondary battery.
  • Patent Document 1 describes a positive electrode active material made of a composite metal oxide, a conductive agent made of a higher-order structure type carbon black, and a ternary or more ternary material containing at least vinylidene fluoride, tetrafluoroethylene, and a flexibility-modified fluorine-containing monomer.
  • a positive electrode mixture for non-aqueous batteries is described, which is prepared by adding 0.5 to 10 parts by weight of an organic acid per 100 parts by weight of a conductive additive to a mixture consisting of a binder made of a fluorine-based copolymer and an organic solvent. ing.
  • a slurry for an electrode mixture for a lithium secondary battery with characteristics is described.
  • the present disclosure aims to provide an electrode mixture that has a well-balanced property of not easily changing viscosity and the ability to form an electrode material layer that adheres to a current collector with high peel strength.
  • an electrode mixture containing a binder (A), an electrode active material (B), and an additive (C), wherein the binder (A) contains vinylidene fluoride units.
  • an electrode mixture containing a fluorine-containing polymer in which the additive (C) contains a polyhydric carboxylic acid (C1) and a fluorine-free polymer containing an unsaturated monocarboxylic acid unit (C2). Ru.
  • an electrode mixture that has a well-balanced property of not easily changing viscosity and the ability to form an electrode material layer that adheres to a current collector with high peel strength.
  • Patent Document 1 discloses that the addition of a small amount of organic acid effectively prevents floating of a positive electrode mixture containing higher-order structure carbon black as a conductive agent when applied on a current collector, and prevents it from floating due to drying. It is described that cracking during formation of a thick positive electrode mixture layer is effectively prevented. Further, Patent Document 2 describes that a solvent-soluble thermoplastic resin functions to improve adhesiveness with a current collector.
  • the electrode mixture of the present disclosure is an electrode mixture containing a binder (A), an electrode active material (B), and an additive (C), where the additive (C) is a polyhydric carboxylic acid. (C1) and a fluorine-free polymer (C2) containing unsaturated monocarboxylic acid units.
  • the additive (C) is a polyhydric carboxylic acid.
  • C1 a fluorine-free polymer
  • C2 containing unsaturated monocarboxylic acid units.
  • Binder (A) The binder (A) used in the present disclosure contains a fluoropolymer containing vinylidene fluoride units (VdF).
  • the fluoropolymer may be a VdF homopolymer consisting only of VdF units, or a polymer containing VdF units and other monomer units.
  • Other monomers may be monomers that can be copolymerized with VdF, and may be fluorinated monomers (excluding VdF) or non-fluorinated monomers. Good too.
  • fluorinated monomers examples include tetrafluoroethylene (TFE), vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene (CTFE), fluoroalkyl vinyl ether, and hexafluoropropylene (HFP). , (perfluoroalkyl)ethylene, 2,3,3,3-tetrafluoropropene and trans-1,3,3,3-tetrafluoropropene.
  • the fluoroalkyl vinyl ether is preferably a fluoroalkyl vinyl ether having a fluoroalkyl group having 1 to 5 carbon atoms, and is selected from the group consisting of perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether). At least one selected type is more preferred.
  • TFE and CTFE are used because they are less likely to change in viscosity and can form an electrode material layer that adheres to the current collector with higher peel strength.
  • 2,3,3,3-tetrafluoropropene, HFP and fluoroalkyl vinyl ether and more preferably at least one selected from the group consisting of TFE and HFP. Particularly preferred.
  • the fluorinated monomer (excluding VdF) may or may not have a polar group.
  • Non-fluorinated monomers include non-fluorinated monomers that do not have polar groups such as ethylene and propylene, and non-fluorinated monomers that have polar groups (hereinafter sometimes referred to as polar group-containing monomers). etc.
  • the polar group is introduced into the fluoropolymer, thereby making it possible to form an electrode material layer that adheres to the current collector with even higher peel strength.
  • the polar group is preferably at least one selected from the group consisting of a carbonyl group-containing group, an epoxy group, a hydroxy group, a sulfonic acid group, a sulfuric acid group, a phosphoric acid group, an amino group, an amide group, and an alkoxy group; At least one selected from the group consisting of a containing group, an epoxy group, and a hydroxy group is more preferable, and a carbonyl group-containing group is even more preferable.
  • the hydroxy group does not include a hydroxy group that forms part of the carbonyl group-containing group.
  • the above-mentioned amino group is a monovalent functional group obtained by removing hydrogen from ammonia, a primary amine, or a secondary amine.
  • the carbonyl group-containing group is preferably a group represented by the general formula: -COOR (R represents a hydrogen atom, an alkyl group, or a hydroxyalkyl group) or a carboxylic acid anhydride group, and is represented by the general formula: -COOR. More preferred are groups such as The number of carbon atoms in the alkyl group and hydroxyalkyl group is preferably 1 to 16, more preferably 1 to 6, and still more preferably 1 to 3.
  • group represented by the general formula -COOR examples include -COOCH 2 CH 2 OH, -COOCH 2 CH(CH 3 )OH, -COOCH(CH 3 )CH 2 OH, -COOH, -COOCH 3 , -COOC 2 H 5 and the like.
  • group represented by the general formula -COOR is -COOH or contains -COOH, -COOH may be a carboxylate such as a metal carboxylate or an ammonium carboxylate.
  • the carbonyl group-containing group has the general formula: -X-COOR
  • X is an atomic group with a molecular weight of 500 or less whose main chain has 1 to 20 atoms
  • R is a hydrogen atom, an alkyl group, or It may be a group represented by (representing a hydroxyalkyl group).
  • the number of carbon atoms in the alkyl group and hydroxyalkyl group is preferably 1 to 16, more preferably 1 to 6, and still more preferably 1 to 3.
  • the above amide group is a group represented by the general formula: -CO-NRR' (R and R' independently represent a hydrogen atom or a substituted or unsubstituted alkyl group), or a group represented by the general formula: - A bond represented by CO-NR"- (R" represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group) is preferred.
  • polar group-containing monomers examples include hydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate and 2-hydroxypropyl acrylate; unsaturated dibasic acids such as maleic acid, maleic anhydride, citraconic acid, and citraconic anhydride; methylidene; Alkylidene malonic acid esters such as dimethyl malonate; vinyl carboxyalkyl ethers such as vinyl carboxymethyl ether and vinyl carboxyethyl ether; carboxyalkyl (meth)acrylates such as 2-carboxyethyl acrylate and 2-carboxyethyl methacrylate; acryloyloxyethyl succinate Acids, (meth)acryloyloxyalkyldicarboxylic acid esters such as methacryloyloxyethylsuccinic acid, acryloyloxyethyl phthalic acid, and methacryloyloxyethyl phthalic acid; maleic acid monomethyl
  • (meth)acrylic acid means either acrylic acid or methacrylic acid.
  • (Meta) in other compound names is interpreted in the same manner.
  • the number of atoms in the main chain of the atomic group is the number of atoms in the linear skeleton portion, and the oxygen atoms forming the carbonyl group and the hydrogen atoms forming the methylene group are not included in the number of atoms in the main chain.
  • the monomer (A1) is acryloyloxyethylphthalic acid
  • the straight chain skeleton is -C-OCCO-C-CC- and the number of atoms is 8.
  • the general formula (A1) is used because the viscosity is less likely to change and an electrode mixture can be obtained that can form an electrode material layer that adheres to the current collector with higher peel strength.
  • Monomer (A1) represented by is preferred.
  • Y represents an inorganic cation and/or an organic cation.
  • inorganic cations include cations such as H, Li, Na, K, Mg, Ca, Al, and Fe.
  • organic cations include cations such as NH 4 , NH 3 R 5 , NH 2 R 5 2 , NHR 5 3 , and NR 5 4 (R 5 independently represents an alkyl group having 1 to 4 carbon atoms).
  • R 5 independently represents an alkyl group having 1 to 4 carbon atoms.
  • Y H, Li, Na, K, Mg, Ca, Al, NH4 are preferable, H, Li, Na, K, Mg, Al, NH4 are more preferable, and H, Li, Al, NH4 are preferable. It is more preferred, and H is particularly preferred. Note that, for convenience, specific examples of inorganic cations and organic cations are described with symbols and valences omitted.
  • R 1 to R 3 independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
  • the alkyl group is preferably a methyl group or an ethyl group.
  • R 1 and R 2 are preferably independently a hydrogen atom, a methyl group or an ethyl group, and R 3 is preferably a hydrogen atom or a methyl group.
  • X is a single bond or an atomic group whose main chain is composed of 1 to 20 atoms and has a molecular weight of 500 or less.
  • the atomic group includes a hydrocarbon group having 1 to 8 carbon atoms, a heteroatom, or at least one heteroatom selected from the group consisting of an oxygen atom, a sulfur atom, a nitrogen atom, and a phosphorus atom, and the number of atoms is An atomic group containing 1 to 20 main chains and having a molecular weight of 500 or less is preferred.
  • the hydrocarbon group is a divalent hydrocarbon group.
  • the number of carbon atoms in the hydrocarbon group is preferably 4 or less.
  • Examples of the hydrocarbon group include alkylene groups and alkenylene groups having the above-mentioned number of carbon atoms, and among them, at least one selected from the group consisting of methylene group, ethylene group, ethylidene group, propylidene group, and isopropylidene group.
  • at least one selected from the group consisting of a methylene group and an ethylene group is more preferable.
  • the heteroatom is preferably at least one selected from the group consisting of an oxygen atom, a sulfur atom, a nitrogen atom, and a phosphorus atom, and an oxygen atom is more preferable.
  • the hetero atom in the atomic group is preferably an oxygen atom.
  • the side chain represented by the general formula: -X-COOY in general formula (A1) is preferably one of the following.
  • the monomer (A1) is a (meth)acrylamide compound such as N-carboxyethyl (meth)acrylamide; a thio(meth)acrylate compound such as carboxyethylthio(meth)acrylate; Vinyl carboxyalkyl ethers such as vinyl carboxymethyl ether and vinyl carboxyethyl ether; 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, acryloyloxyethyl succinic acid, methacryloyloxyethyl succinic acid, acryloyloxypropyl succinic acid, Examples include methacryloyloxypropyl succinic acid, acryloyloxyethylphthalic acid, and methacryloyloxyethylphthalic acid.
  • the monomer (A1) includes 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, acryloyloxyethylsuccinic acid, methacryloyloxyethylsuccinic acid, acryloyloxypropylsuccinic acid, Methacryloyloxypropylsuccinic acid is preferred.
  • the monomer (A1) is preferably a monomer (A1) in the general formula (A1) in which X is a single bond or a hydrocarbon group having 1 to 8 carbon atoms.
  • (meth)acrylic acid is used because it is less likely to change viscosity and can form an electrode material layer that adheres to the current collector with even higher peel strength. and its salts, vinyl acetic acid (3-butenoic acid) and its salts, 3-pentenoic acid and its salts, 4-pentenoic acid and its salts, 3-hexenoic acid and its salts, 4-heptenoic acid and its salts, and At least one selected from the group consisting of 5-hexenoic acid and its salts is more preferred, and (meth)acrylic acid and its salts are even more preferred.
  • the content of the polar group-containing monomer units in the fluoropolymer is preferably 0.05 to 2.0 mol%, more preferably 0.10 mol% or more based on the total monomer units. It is more preferably 0.25 mol% or more, particularly preferably 0.40 mol% or more, and more preferably 1.5 mol% or less.
  • the content of the polar group-containing monomer unit in the fluoropolymer can be measured by acid-base titration of the acid group, for example, when the polar group is an acid group such as a carboxylic acid.
  • the other monomer is preferably at least one selected from the group consisting of TFE, CTFE, (meth)acrylic acid, 2,3,3,3-tetrafluoropropene, HFP, and fluoroalkyl vinyl ether.
  • (Meth)acrylic acid includes acrylic acid and methacrylic acid.
  • the content of other monomer units in the fluoropolymer is preferably 0.0001 to 50.0 mol%, more preferably 0.01 mol% or more based on the total monomer units. , more preferably 0.10 mol% or more, more preferably 45.0 mol% or less, still more preferably 40.0 mol% or less, particularly preferably 35.0 mol% or less.
  • the content of VdF units in the fluoropolymer is 50.0 to 99.9999 mol% based on the total monomer units, and more Preferably it is 55.0 mol% or more, more preferably 60.0 mol% or more, particularly preferably 65.0 mol% or more, more preferably 99.99 mol% or less, and even more preferably It is 99.90 mol% or less.
  • the content of the fluorinated monomer unit is preferably 0.0001 to 50% of the total monomer units. .0 mol%, more preferably 2.0 mol% or more, still more preferably 3.0 mol% or more, particularly preferably 4.0 mol% or more, more preferably 45.0 mol%. % or less, more preferably 40.0 mol% or less, particularly preferably 35.0 mol% or less.
  • the content of VdF units in the fluoropolymer is 50.0 to 99.0% with respect to all monomer units. 999 mol%, more preferably 55.0 mol% or more, still more preferably 60.0 mol% or more, particularly preferably 65.0 mol% or more, more preferably 98.0 mol% or less, more preferably 97.0 mol% or less, particularly preferably 96.0 mol% or less.
  • the content of non-fluorinated monomer units is the total monomer unit. , preferably 0.0001 to 50.0 mol%, more preferably 0.01 mol% or more, still more preferably 0.10 mol% or more, and even more preferably 5.0 mol%. or less, more preferably 3.0 mol% or less, particularly preferably 1.5 mol% or less.
  • the content of VdF units in the fluoropolymer is preferably 50.0 with respect to all monomer units. ⁇ 99.999 mol%, more preferably 95.0 mol% or more, still more preferably 97.0 mol% or more, particularly preferably 98.5 mol% or more, and more preferably 99.999 mol%. It is 99 mol% or less, more preferably 99.90 mol% or less.
  • the composition of the fluoropolymer can be measured, for example, by 19 F-NMR measurement.
  • the fluorine-containing polymer contains a polar group-containing monomer unit as another monomer unit
  • the content of the polar group-containing monomer unit is determined, for example, when the polar group is an acid group such as a carboxylic acid. In some cases, it can be determined by acid-base titration of acid groups.
  • the weight average molecular weight (in terms of polystyrene) of the fluoropolymer is preferably 10,000 to 3,000,000, more preferably 30,000 or more, even more preferably 50,000 or more, particularly preferably 200,000 or more, and more preferably 2,400,000. or less, more preferably 2,200,000 or less, particularly preferably 2,000,000 or less.
  • the weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.
  • the fluorine-containing polymer containing vinylidene fluoride units contained in the binder (A) may be polyvinylidene fluoride.
  • polyvinylidene fluoride is a fluoropolymer containing 98.0 mol% or more of VdF units based on all monomer units.
  • Polyvinylidene fluoride may be a VdF homopolymer consisting only of VdF units, or a polymer containing VdF units and other monomer units.
  • Other monomers may be monomers that can be copolymerized with VdF, and may be fluorinated monomers (excluding VdF) or non-fluorinated monomers. Good too. As other monomers, those mentioned above can be used.
  • polyvinylidene fluoride examples include CTFE, fluoroalkyl vinyl ether, HFP, 2,3,3,3-tetrafluoropropene, and the monomer represented by general formula (A1). At least one selected from the group consisting of mer (A1) is preferred. Moreover, it is preferable that polyvinylidene fluoride does not contain TFE units.
  • the content of other monomer units in polyvinylidene fluoride is 0 to 2.0 mol%, preferably 0 to 1.5 mol%, more preferably It is 0 to 1.0 mol%.
  • the content of VdF units in polyvinylidene fluoride is 98.0 mol% or more, preferably 98.5 mol% or more, more preferably 99.0 mol% or more, based on all monomer units. and is preferably 100 mol% or less.
  • the weight average molecular weight (in terms of polystyrene) of polyvinylidene fluoride is preferably 50,000 to 3,000,000, more preferably 80,000 or more, even more preferably 100,000 or more, particularly preferably 200,000 or more, and more preferably 2,400,000. or less, more preferably 2,200,000 or less, particularly preferably 2,000,000 or less.
  • the weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.
  • Polyvinylidene fluoride is composed only of vinylidene fluoride units because its viscosity is less likely to change, and furthermore, it provides an electrode mixture that can form an electrode material layer that adheres to the current collector with higher peel strength.
  • At least one type selected from the group consisting of fluorine-containing polymers containing units based on the monomer (A1) is preferable, since it has an excellent balance between a low rate of change in viscosity and high adhesion of the electrode material layer.
  • At least one member selected from the group consisting of fluorine-containing polymers consisting only of vinylidene fluoride units and fluorine-containing polymers containing vinylidene fluoride units and fluorinated monomer units (excluding vinylidene fluoride units) is more preferable.
  • the binder (A) contains a fluorine-containing copolymer.
  • a fluorine-containing copolymer is a fluorine-containing copolymer containing less than 98.0 mol% of VdF units based on all monomer units. Therefore, a fluorine-containing copolymer is a polymer containing VdF units and other monomer units.
  • Other monomers may be monomers that can be copolymerized with VdF, and may be fluorinated monomers (excluding VdF) or non-fluorinated monomers. Good too. As other monomers, those mentioned above can be used.
  • fluorinated monomers including VdF
  • HFP fluoroalkyl vinyl ether
  • CTFE fluoroalkyl vinyl ether
  • 2,3,3 At least one selected from the group consisting of 3-tetrafluoropropene is more preferred, and TFE is even more preferred.
  • the content of other monomer units in the fluorine-containing copolymer is preferably 43.0 mol% or less, more preferably 40.0 mol% or less, and even more preferably is 37.0 mol% or less, more than 2.0 mol%, preferably 3.0 mol% or more, more preferably 5.0 mol% or more, and even more preferably 10.0 mol%. That's all.
  • the content of VdF units in the fluorine-containing copolymer is preferably 57.0 mol% or more, more preferably 60.0 mol% or more, still more preferably 63.0 mol% or more, based on all monomer units. 0 mol% or more, less than 98.0 mol%, preferably 97.0 mol% or less, more preferably 95.0 mol% or less, even more preferably 90.0 mol% or less .
  • the fluorine-containing copolymer may further contain the above-mentioned polar group-containing monomer unit.
  • the content of polar group-containing monomer units in the fluorine-containing copolymer is preferably 0.05 to 2.0 mol%, more preferably 0.10 mol% or more based on the total monomer units. It is more preferably 0.25 mol% or more, particularly preferably 0.40 mol% or more, and more preferably 1.5 mol% or less.
  • the weight average molecular weight (in terms of polystyrene) of the fluorine-containing copolymer is preferably 50,000 to 3,000,000, more preferably 80,000 or more, even more preferably 100,000 or more, particularly preferably 200,000 or more, and more preferably It is 2,400,000 or less, more preferably 2,200,000 or less, particularly preferably 2,000,000 or less.
  • the weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.
  • fluorine-containing copolymer examples include VdF/TFE copolymer, VdF/HFP copolymer, VdF/TFE/HFP copolymer, VdF/TFE/(meth)acrylic acid copolymer, and VdF/HFP/ (meth)acrylic acid copolymer, VdF/CTFE copolymer, VdF/TFE/4-pentenoic acid copolymer, VdF/TFE/3-butenoic acid copolymer, VdF/TFE/HFP/(meth)acrylic Acid copolymer, VdF/TFE/HFP/4-pentenoic acid copolymer, VdF/TFE/HFP/3-butenoic acid copolymer, VdF/TFE/2-carboxyethyl acrylate copolymer, VdF/TFE/ Examples include HFP/2-carboxyethyl acrylate copolymer, VdF/TFE
  • VdF/TFE copolymers VdF/HFP copolymers, VdF/fluoroalkyl vinyl ether copolymers, VdF/CTFE copolymers, and VdF/2,3,3 , 3-tetrafluoropropene copolymer is preferred, and VdF/TFE copolymer is more preferred.
  • the VdF/TFE copolymer contains VdF units and TFE units.
  • the content of VdF units is preferably 57.0 mol% or more, more preferably 60.0 mol% or more, and even more preferably It is 63.0 mol% or more, preferably less than 98.0 mol%, more preferably 90.0 mol% or less, and still more preferably 85.0 mol% or less.
  • the content of TFE units is preferably more than 2.0 mol%, more preferably 10.0 mol% or more, and even more preferably It is 15.0 mol% or more, preferably 43.0 mol% or more, more preferably 40.0 mol% or less, and even more preferably 37.0 mol% or less.
  • the VdF/TFE copolymer may contain units based on monomers copolymerizable with VdF and TFE (excluding VdF and TFE).
  • the content of units based on monomers copolymerizable with VdF and TFE is preferably 3.0 mol % or less based on the total monomer units of the VdF/TFE copolymer.
  • Examples of monomers copolymerizable with VdF and TFE include the above-mentioned fluorinated monomers and the above-mentioned non-fluorinated monomers.
  • the monomer copolymerizable with VdF and TFE is preferably at least one selected from the group consisting of fluorinated monomers and polar group-containing monomers, including HFP, 2,3,3, At least one selected from the group consisting of 3-tetrafluoropropene and monomer (A1) is more preferred.
  • the weight average molecular weight (in terms of polystyrene) of the VdF/TFE copolymer is preferably 50,000 to 2,000,000, more preferably 80,000 or less, still more preferably 100,000 or less, and even more preferably 1,700,000 or more. Preferably it is 1,500,000 or more.
  • the weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.
  • the binder (A) contains polyvinylidene fluoride and a fluorine-containing copolymer.
  • the binder (A) contains polyvinylidene fluoride and a fluorine-containing copolymer, changes in the viscosity of the electrode mixture can be further suppressed.
  • polyvinylidene fluoride and fluorine-containing copolymers can be used to obtain an electrode mixture whose viscosity is less likely to change and which can form an electrode material layer that adheres to the current collector with even higher peel strength.
  • the mass ratio to the polymer is preferably 99/1 to 1/99, more preferably 97/3 or less, and even more preferably 95/5 or less. Still more preferably 90/10 or less, more preferably 3/97 or more, still more preferably 5/95 or more, still more preferably 10/90 or more.
  • the content of the binder (A) in the electrode mixture is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably It is 5% by mass or less, preferably 0.1% by mass or more, and more preferably 0.5% by mass or more.
  • Electrode active material (B) The electrode active material used in the present disclosure may be a positive electrode active material or a negative electrode active material.
  • the positive electrode active material a material that can electrochemically insert and release lithium ions can be used, preferably a lithium composite oxide, and more preferably a lithium transition metal composite oxide.
  • a lithium-containing transition metal phosphate compound is also preferable. It is also preferable that the positive electrode active material is a material containing lithium and at least one transition metal, such as a lithium transition metal composite oxide or a lithium-containing transition metal phosphate compound.
  • the transition metal of the lithium transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc.
  • specific examples of the lithium transition metal composite oxide include lithium cobalt such as LiCoO2.
  • the above substituted materials include lithium-nickel-manganese composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-cobalt-manganese composite oxide, lithium-manganese-aluminum composite oxide, and lithium-titanium composite oxide.
  • Examples include composite oxides, more specifically, LiNi 0.5 Mn 0.5 O 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.33 Co 0.33 Mn 0 .33 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , Examples include LiMn 1.8 Al 0.2 O 4 , LiMn 1.5 Ni 0.5 O 4 , Li 4 Ti 5 O 12 , LiNi 0.82 Co 0.15 Al 0.03 O 2 and the like.
  • the transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc.
  • specific examples of the lithium-containing transition metal phosphate compound include, for example, LiFePO 4 , Iron phosphates such as Li 3 Fe 2 (PO 4 ) 3 and LiFeP 2 O 7 , cobalt phosphates such as LiCoPO 4 , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are replaced with Al. , Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, and other metals substituted.
  • LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiNi 0.82 Co 0.15 Al 0.03 O 2 , LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 and LiFePO 4 are preferred.
  • a lithium metal oxide represented by the general formula (B1) is preferably mentioned.
  • z is a coefficient that satisfies 0.5 ⁇ z ⁇ 1, and since a secondary battery with a higher capacity can be obtained, z is preferably 0.6 ⁇ z ⁇ 1, and more Preferably 0.7 ⁇ z ⁇ 0.9.
  • the viscosity of the electrode mixture of the present disclosure does not easily change even when a lithium metal oxide containing a large amount of Ni is used as the electrode active material (B).
  • Examples of the lithium metal oxide represented by the general formula (B1) include LiNi 0.80 Co 0.15 Al 0.05 O 2 , LiNi 0.82 Co 0.15 Al 0.03 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , and LiNi 0.90 Mn 0. At least one selected from the group consisting of 05 Co 0.05 O 2 is preferable, and LiNi 0.82 Co 0.15 Al 0.03 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , and at least one selected from the group consisting of LiNi 0.8 Mn 0.1 Co 0.1 O 2 is more preferred.
  • a cathode active material to which a substance having a composition different from that of the substance constituting the main cathode active material is attached to the surface.
  • Substances attached to the surface include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate.
  • sulfates such as aluminum sulfate
  • carbonates such as lithium carbonate, calcium carbonate, magnesium carbonate, and the like.
  • These surface-adhering substances can be prepared by, for example, dissolving or suspending them in a solvent, adding them to the positive electrode active material and drying them, or dissolving or suspending a surface-adhering substance precursor in a solvent, adding them to the positive electrode active material by impregnating them, and then heating them. It can be attached to the surface of the positive electrode active material by a reaction method such as a reaction method, a method of adding it to a positive electrode active material precursor and firing it at the same time, and the like.
  • the amount of the surface-attached substance is preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more as a lower limit, and preferably 20% or less as an upper limit, more preferably 10% by mass relative to the positive electrode active material. % or less, more preferably 5% or less.
  • Substances attached to the surface can suppress the oxidation reaction of the non-aqueous electrolyte on the surface of the positive electrode active material and improve battery life, but if the amount attached is too small, the effect will not be fully realized. If the amount is too large, the resistance may increase because the ingress and egress of lithium ions is inhibited.
  • the shape of the particles of the positive electrode active material can be the conventionally used shapes such as lumps, polyhedrons, spheres, ellipsoids, plates, needles, columns, etc. Among them, primary particles aggregate and form secondary particles. Preferably, the shape of the secondary particles is spherical or ellipsoidal. Normally, as an electrochemical element is charged and discharged, the active material in the electrode expands and contracts, so the stress tends to cause deterioration such as destruction of the active material and breakage of conductive paths. Therefore, rather than a single-particle active material consisting of only primary particles, it is preferable to use a material in which primary particles are aggregated to form secondary particles in order to alleviate the stress of expansion and contraction and prevent deterioration.
  • spherical or elliptic spherical particles are less oriented during electrode molding than plate-like equiaxed particles, so the expansion and contraction of the electrode during charging and discharging is less, and it is also easier to fabricate the electrode. Even when mixed with a conductive agent at the time of mixing, it is preferable because it is easy to mix uniformly.
  • the tap density of the positive electrode active material is usually 1.3 g/cm 3 or more, preferably 1.5 g/cm 3 or more, more preferably 1.6 g/cm 3 or more, and most preferably 1.7 g/cm 3 or more. . If the tap density of the positive electrode active material is below the above lower limit, the required amount of dispersion medium and conductive agent and copolymer will increase when forming the positive electrode material layer, and the amount of the positive electrode active material in the positive electrode material layer will increase. The filling rate may be constrained and the battery capacity may be constrained. By using metal composite oxide powder with high tap density, a high-density positive electrode material layer can be formed.
  • the tap density of the positive electrode active material is determined by passing the sample through a sieve with an opening of 300 ⁇ m, dropping it into a 20 cm 3 tapping cell to fill the cell volume, and then using a powder density measuring device (for example, a tap density meter manufactured by Seishin Enterprise Co., Ltd.). ), tapping with a stroke length of 10 mm is performed 1000 times, and the density determined from the volume at that time and the weight of the sample is defined as the tapped density.
  • a powder density measuring device for example, a tap density meter manufactured by Seishin Enterprise Co., Ltd.
  • the median diameter d50 of the particles of the positive electrode active material is usually 0.1 ⁇ m or more, preferably 0.5 ⁇ m or more, more preferably 1 ⁇ m. Above, it is most preferably 3 ⁇ m or more, and usually 20 ⁇ m or less, preferably 18 ⁇ m or less, more preferably 16 ⁇ m or less, and most preferably 15 ⁇ m or less. If it is below the above lower limit, it may not be possible to obtain a high bulk density product, and if it exceeds the upper limit, it will take time for the lithium in the particles to diffuse, resulting in a decrease in battery performance or in the production of the battery's positive electrode, i.e., the active material.
  • the median diameter d50 in the present disclosure is measured by a known laser diffraction/scattering particle size distribution measuring device.
  • LA-920 manufactured by HORIBA as a particle size distribution meter
  • a 0.1% by mass sodium hexametaphosphate aqueous solution is used as the dispersion medium used during measurement, and the measured refractive index is set to 1.24 after 5 minutes of ultrasonic dispersion. It is measured by
  • the average primary particle diameter of the positive electrode active material is usually 0.01 ⁇ m or more, preferably 0.05 ⁇ m or more, more preferably 0.08 ⁇ m or more, Most preferably it is 0.1 ⁇ m or more, usually 3 ⁇ m or less, preferably 2 ⁇ m or less, more preferably 1 ⁇ m or less, and most preferably 0.6 ⁇ m or less. If the above upper limit is exceeded, it may be difficult to form spherical secondary particles, which may adversely affect powder filling properties or significantly reduce the specific surface area, increasing the possibility that battery performance such as output characteristics will deteriorate. be.
  • the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph with a magnification of 10,000 times, the longest value of the intercept by the left and right boundaries of the primary particles with respect to the horizontal straight line is determined for any 50 primary particles, and the average value is calculated. It will be done.
  • the BET specific surface area of the positive electrode active material is 0.2 m 2 /g or more, preferably 0.3 m 2 /g or more, more preferably 0.4 m 2 /g or more, and 4.0 m 2 /g or less, preferably 2 m 2 /g or more. .5 m 2 /g or less, more preferably 1.5 m 2 /g or less. If the BET specific surface area is smaller than this range, the battery performance tends to deteriorate, and if it is larger, it becomes difficult to increase the tap density, which may easily cause problems in coating properties when forming the positive electrode material layer.
  • BET specific surface area is calculated by pre-drying the sample at 150°C for 30 minutes under nitrogen flow using a surface area meter (for example, a fully automatic surface area measurement device manufactured by Okura Riken), and then calculating the relative pressure of nitrogen with respect to atmospheric pressure. It is defined as a value measured by a nitrogen adsorption BET one-point method using a gas flow method using a nitrogen-helium mixed gas that has been accurately adjusted to a value of 0.3.
  • a method for producing the positive electrode active material a method commonly used for producing inorganic compounds is used.
  • various methods can be used to produce spherical or elliptic spherical active materials.
  • a spherical precursor is prepared and collected by dissolving or pulverizing and dispersing it in a solvent, adjusting the pH while stirring, and drying this as necessary.
  • a method of obtaining an active material by adding a source and firing at a high temperature, transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, oxides, etc., and raw materials of other elements as necessary, are mixed in a solvent such as water.
  • a Li source such as LiOH, Li 2 CO 3 , or LiNO 3 is added to this, and the mixture is fired at a high temperature.
  • transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, and oxides, Li sources such as LiOH, Li 2 CO 3 , LiNO 3 , and other materials as necessary
  • a method of dissolving or pulverizing and dispersing the elemental raw material in a solvent such as water, drying and molding it with a spray dryer, etc. to obtain a spherical or ellipsoidal precursor, and firing this at a high temperature to obtain an active material. etc.
  • one type of positive electrode active material may be used alone, or two or more types of positive electrode active materials having different compositions or different powder physical properties may be used in any combination and ratio.
  • the content of the binder is preferably 0.01 to 5.0 parts by mass, more preferably 100 parts by mass of the positive electrode active material. It is 0.1 to 2.0 parts by mass.
  • negative electrode active material examples include negative electrode active materials that exhibit a potential of 2.5 V or less based on Li when alloyed with Li or combined with Li.
  • a negative electrode active material containing metal can be used as the negative electrode active material.
  • the metal contained in the negative electrode active material is usually a metal that can be electrochemically alloyed with an alkali metal such as Li or Na.
  • the negative electrode active material simple metals that can be electrochemically alloyed with Li such as Si, Zn, Sn, W, Al, Sb, Ge, Bi, and In; Si, Zn, Sn, W, Al, Sb, Examples include alloys containing Ge, Bi, In, etc.; lithium alloys such as lithium aluminum alloys and lithium tin alloys; metal oxides such as tin oxide and silicon oxide; lithium titanate; and the like. One or more of these can be used as the negative electrode active material.
  • the negative electrode active material is preferably a compound containing at least one element selected from the group consisting of Si, Sn, V, Nb, and Ti, including Si (simple Si), an oxide of Si, and an alloy containing Si. , Sn (Sn carrier), an oxide of Sn, and an alloy containing Sn are more preferred, and at least one selected from the group consisting of Si and SiO x (0 ⁇ x ⁇ 2) is even more preferred.
  • a carbonaceous material such as graphite powder may be used as the negative electrode active material.
  • Carbonaceous materials can be used with negative electrode active materials containing metals. Examples of carbonaceous materials include natural graphite, artificial carbonaceous substances, artificial graphite substances, and carbonaceous substances ⁇ for example, natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, or oxidized pitches of these pitches.
  • pyrolysis products of organic matter such as needle coke, pitch coke, carbon materials partially graphitized from these, furnace black, acetylene black, Ketjen black, pitch-based carbon fiber, and carbonizable organic matter (for example, from soft pitch to Coal tar pitch up to hard pitch, coal-based heavy oil such as dry-distilled liquefied oil, straight-run heavy oil such as normal pressure residual oil, vacuum residual oil, ethylene tar, etc. produced as a by-product during thermal decomposition of crude oil, naphtha, etc.
  • organic matter such as needle coke, pitch coke, carbon materials partially graphitized from these, furnace black, acetylene black, Ketjen black, pitch-based carbon fiber, and carbonizable organic matter
  • coal-based heavy oil such as dry-distilled liquefied oil, straight-run heavy oil such as normal pressure residual oil, vacuum residual oil, ethylene tar, etc. produced as a by-product during thermal decomposition of crude oil, naphtha, etc.
  • the mass ratio of the metal-containing negative electrode active material and the carbonaceous material is preferably 1/99 to 99/1, and more preferably The ratio is preferably 5/95 to 95/5, more preferably 10/10 to 90/10.
  • the content of the binder is preferably 0.01 to 20.0 parts by mass, more preferably It is 0.1 to 10.0 parts by mass.
  • the content of the electrode active material (positive electrode active material or negative electrode active material) is preferably 40% by mass or more in the solid content of the electrode mixture in order to increase the capacity of the obtained electrode.
  • the mass ratio (A/B) of the binder (A) and the electrode active material (B) is such that the electrode material layer can form an electrode material layer that adheres to the current collector with even higher peel strength. Since a mixture can be obtained, the ratio is preferably 0.01/99.99 to 10/90, more preferably 0.5/99.5 or more, still more preferably 1/99 or more, and more preferably is 4/96 or less, more preferably 3/97 or less.
  • the electrode mixture may further contain a conductive agent.
  • a conductive agent examples include carbon blacks such as acetylene black and Ketjen black, carbon materials such as graphite, carbon fibers, carbon nanotubes, carbon nanohorns, and graphene.
  • the content of the conductive agent is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 2.0 parts by mass, based on 100 parts by mass of the electrode active material.
  • the electrode mixture of the present disclosure contains a polyhydric carboxylic acid (C1) and a fluorine-free polymer (C2) containing unsaturated monocarboxylic acid units as an additive (C).
  • C polyhydric carboxylic acid
  • C2 fluorine-free polymer
  • the viscosity change rate of the electrode mixture can be lowered.
  • the polycarboxylic acid (C1) and the fluorine-free polymer (C2) to the electrode mixture, only one of the polycarboxylic acid (C1) and the fluorine-free polymer (C2) can be added. It is possible to form an electrode material layer having higher peel strength with respect to the current collector than an electrode material layer formed from the electrode mixture contained therein.
  • the polycarboxylic acid (C1) is a compound having two or more carboxyl groups in the molecule, and may be a saturated polycarboxylic acid or an unsaturated polycarboxylic acid.
  • dicarboxylic acids are preferred, and unsaturated dicarboxylic acids are more preferred.
  • tartaric acid is used because it is less likely to change in viscosity and can form an electrode material layer that adheres to the current collector with higher peel strength.
  • citric acid, oxalic acid, malonic acid, maleic acid, citraconic acid, succinic acid, adipic acid, phthalic acid, isophthalic acid, and terephthalic acid, and tartaric acid is more preferable.
  • the fluorine-free polymer (C2) is a polymer that does not contain fluorine atoms and contains unsaturated monocarboxylic acid units.
  • an unsaturated monocarboxylic acid refers to a compound that does not contain a fluorine atom and has one or more unsaturated bonds and one carboxyl group in the molecule, for example, one (metallic acid) in the molecule.
  • Compounds having an acryloyl group and one carboxyl group are mentioned.
  • the general formula (C2) is used because the viscosity is less likely to change and an electrode material layer that can form an electrode material layer that adheres to the current collector with higher peel strength can be obtained.
  • the represented monomer (C2) is preferred.
  • R 1 to R 3 , X and Y in general formula (C2) include the same ones as R 1 to R 3 , X and Y in general formula (A1), and the same ones are preferable.
  • a monomer (C2) in which X is a single bond or a hydrocarbon group having 1 to 8 carbon atoms is preferable, and a monomer in which X is a single bond. (C2) is more preferred.
  • (meth)acrylic acid is used because it is less likely to change viscosity and can form an electrode material layer that adheres to the current collector with even higher peel strength. and its salts are preferred. That is, as the fluorine-free polymer (C2), poly(meth)acrylic acid is preferable.
  • the fluorine-free polymer (C2) may contain non-fluorinated monomer units (excluding unsaturated monocarboxylic acid units) as well as unsaturated monocarboxylic acid units.
  • non-fluorinated monomer those exemplified as the non-fluorinated monomer that can be contained in the fluoropolymer as the binder (A) can be similarly exemplified.
  • the content of unsaturated monocarboxylic acid units in the fluorine-free polymer (C2) is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, based on all monomer units. It is more preferably 99.0 mol% or more, particularly preferably 99.9 mol% or more, and preferably 100 mol% or less.
  • the content of non-fluorinated monomer units in the fluorine-free polymer (C2) is preferably 10.0 mol% or less, more preferably 5.0 mol% or less, based on all monomer units. It is more preferably 1.0 mol% or less, particularly preferably 0.1 mol% or less, and preferably 0 mol% or more.
  • the number average molecular weight of the fluorine-free polymer (C2) is preferably 1,500,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, preferably 3,000 or more, and more preferably 50,000 or more. , more preferably 100,000 or more. If the number average molecular weight is high, it may be difficult to homogenize the electrode mixture slurry from the viewpoint of solubility, and if the molecular weight is too low, the viscosity of the electrode mixture slurry may become low.
  • the mass ratio ((C1)/(C2)) of the polyhydric carboxylic acid (C1) and the fluorine-free polymer (C2) is such that the viscosity is less likely to change, and it also adheres to the current collector with higher peel strength.
  • the ratio is preferably 1/99 to 99/1, more preferably 3/97 or more, still more preferably 6/94 or more, and still more Preferably 9/91 or more, particularly preferably 15/85 or more, more preferably 97/3 or less, still more preferably 94/6 or less, still more preferably 91/9 or less, especially Preferably it is 85/15 or less.
  • the mass ratio ((C1)/(C2)) of the polyhydric carboxylic acid (C1) and the fluorine-free polymer (C2) is 15/85 to 85/15, the viscosity is even more difficult to change. Furthermore, it is possible to obtain an electrode mixture that can form an electrode material layer that adheres to the current collector with even higher peel strength.
  • the mass ratio ((C1)/(C2)) is most preferably 20/80 or more, and most preferably 80/20 or less.
  • the content of the additive (C) in the electrode mixture is preferably 0.01 to 5.0% by mass based on the mass of the binder (A) and the electrode active material (B) in the electrode mixture. It is more preferably 3.0% by mass or less, still more preferably 2.5% by mass or less, particularly preferably 2.0% by mass or less.
  • the electrode mixture of the present disclosure preferably contains a solvent.
  • the solvent include organic solvents.
  • organic solvents include nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and dimethylformamide; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; ethyl acetate; Ester solvents such as butyl acetate; chain carbonate solvents such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, butyl butyrate, and ethyl acetate; ethylene carbonate, propylene carbonate, 4-fluoro-1,3 dioxolan-2-one Cyclic carbonate esters such as; ether solvents such as tetrahydrofuran and dioxane; ⁇ -methoxy-N,N-dimethylpropionamide, ⁇ -n-butoxy-N,N-dimethylpropionamide, ⁇ -n-hexyl
  • organic solvent a solvent represented by general formula (1) can also be used.
  • R 11 , R 12 and R 13 are independently H or a monovalent substituent, provided that the total number of carbon atoms in R 11 , R 12 and R 13 is 6 or more, and R 11 , At least one of R 12 and R 13 is an organic group having a carbonyl group. Any two of R 11 , R 12 and R 13 may be combined to form a ring.
  • Examples of the solvent represented by the general formula (1) include 3-methoxy-N,N-dimethylpropanamide, N-ethyl-2-pyrrolidone (NEP), N-butyl-2-pyrrolidone (NBP), and acryloylmorpholine.
  • N-cyclohexyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 3-butoxy-N,N-dimethylpropanamide, N,N,N' ,N'-tetraethylurea, N,N-dimethylacetoaceta At least one selected from the group consisting of amide, N-octyl-2-pyrrolidone and N,N-diethylacetamide is preferred.
  • N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and the solvent represented by general formula (1) are used as solvents because of their excellent coating properties.
  • the content of the solvent is determined in consideration of the applicability to the current collector, the ability to form a thin film after drying, etc.
  • the total content of the binder (A) and the electrode active material (B) is preferably 50 to 90% by mass, more preferably 60 to 90% by mass based on the solid content of the electrode mixture. It is 85% by mass, more preferably 65 to 80% by mass.
  • the total content of the additive (C) and the solvent is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and even more preferably 20 to 35% by mass. It is mass.
  • the solid content concentration is preferably 95% by mass or less, more preferably 90% by mass or less, preferably 50% by mass or more, and more preferably 60% by mass or more. .
  • the viscosity of the electrode mixture is preferably 1000 to 80000 mPa ⁇ s, more preferably 3000 mPa ⁇ s or more, since it is easy to apply and it is also easy to obtain a positive electrode material layer having a desired thickness. , more preferably 5,000 mPa ⁇ s or more, more preferably 70,000 mPa ⁇ s or less, still more preferably 60,000 mPa ⁇ s or less.
  • the above viscosity can be measured at 25°C using a B-type viscometer.
  • the electrode mixture of the present disclosure may be an electrode mixture for secondary batteries, or may be an electrode mixture for lithium ion secondary batteries. Further, the electrode mixture of the present disclosure may be a positive electrode mixture used for producing a positive electrode or a negative electrode mixture used for producing a negative electrode, but is preferably a positive electrode mixture.
  • the electrode of the present disclosure includes a current collector and an electrode material layer.
  • the electrode material layer is formed using the electrode mixture of the present disclosure, and may be provided on one side or both sides of the current collector.
  • the electrode of the present disclosure may be a positive electrode including a positive electrode material layer, or may be a negative electrode including a negative electrode material layer.
  • the density of the electrode material layer is preferably 1.5 to 5.0 g/cm 3 , more preferably 2.0 to 4.5 g/cm 3 .
  • the density of the electrode material layer can be calculated from the mass and volume of the electrode material layer.
  • the thickness of the electrode material layer is preferably 20 ⁇ m or more, more preferably 30 ⁇ m or more, still more preferably 40 ⁇ m or more, and particularly preferably 45 ⁇ m or more, since even higher battery characteristics can be obtained. is 170 ⁇ m or less, more preferably 150 ⁇ m or less. Moreover, the thickness of the electrode material layer may be 85 ⁇ m or less, or less than 69 ⁇ m.
  • the thickness of the electrode material layer can be measured with a micrometer.
  • the thickness of the electrode material layer in the present disclosure is the thickness per one side when the electrode material layer is provided on both sides of the current collector.
  • Examples of the current collector included in the electrode of the present disclosure include metal foils or metal nets made of iron, stainless steel, copper, aluminum, nickel, titanium, etc., and among them, aluminum foil is preferred.
  • the electrode of the present disclosure can be suitably manufactured by a manufacturing method of applying the electrode mixture of the present disclosure to a current collector. After applying the electrode mixture, the coating film may be further dried and the resulting dry coating film may be pressed.
  • the amount of the electrode mixture applied to the current collector is preferably 10 mg/cm 2 or more, more preferably 17.5 mg/cm 2 or more, and preferably 60 mg/cm 2 or less, and more preferably is 50 mg/ cm2 or less.
  • the coating amount of the electrode mixture is the dry weight of the electrode mixture per unit area.
  • a secondary battery including the above electrode is provided.
  • the electrode material layer formed from the electrode mixture of the present disclosure may be a positive electrode material layer or a negative electrode material layer.
  • the secondary battery of the present disclosure includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, and preferably one or both of the positive electrode and the negative electrode is the above electrode. Further, the secondary battery of the present disclosure includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, and preferably the positive electrode is the above electrode. Further, a separator may be interposed between the positive electrode and the negative electrode.
  • Non-aqueous electrolytes include, but are not limited to, propylene carbonate, ethylene carbonate, butylene carbonate, ⁇ -butyl lactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc.
  • solvents can be used. Any conventionally known electrolytes can be used, such as LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiCl, LiBr, CH 3 SO 3 Li, CF 3 SO 3 Li, cesium carbonate, and the like.
  • the electrode of the present disclosure can be suitably used as an electrode for a wound type secondary battery. Further, the secondary battery of the present disclosure may be a wound type secondary battery.
  • the electrode of the present disclosure is useful for nonaqueous electrolyte secondary batteries, not only for lithium ion secondary batteries using the liquid electrolyte described above, but also for polymer electrolyte lithium secondary batteries. It is also useful for electric double layer capacitors.
  • An electrode mixture containing a binder (A), an electrode active material (B) and an additive (C),
  • the binder (A) contains a fluorine-containing polymer containing vinylidene fluoride units
  • An electrode mixture is provided in which the additive (C) contains a polyhydric carboxylic acid (C1) and a fluorine-free polymer (C2) containing unsaturated monocarboxylic acid units.
  • the polycarboxylic acid (C1) is at least one selected from the group consisting of tartaric acid, citric acid, oxalic acid, malonic acid, maleic acid, citraconic acid, succinic acid, adipic acid, phthalic acid, isophthalic acid, and terephthalic acid.
  • An electrode mixture according to the first aspect is provided.
  • An electrode mixture according to the first or second aspect is provided, wherein the polyhydric carboxylic acid (C1) is tartaric acid.
  • the unsaturated monocarboxylic acid unit is a unit based on the monomer (C2) represented by the general formula (C2).
  • C2 the monomer represented by the general formula (C2).
  • the fluorine-free polymer (C2) is polyacrylic acid.
  • any one of the first to fifth aspects wherein the content of the additive (C) is 0.01 to 5.0% by mass with respect to the mass of the binder (A) and the electrode active material (B). provides an electrode mixture.
  • the mass ratio ((C1)/(C2)) of the polyhydric carboxylic acid (C1) and the fluorine-free polymer (C2) is 9/91 to 91/9. An electrode mixture is provided.
  • the electrode mixture according to any one of the first to seventh aspects, wherein the binder (A) contains polyvinylidene fluoride containing 98.0 mol% or more of vinylidene fluoride units as the fluorine-containing polymer.
  • the binder (A) contains polyvinylidene fluoride containing 98.0 mol% or more of vinylidene fluoride units as the fluorine-containing polymer.
  • Polyvinylidene fluoride is a fluorine-containing polymer consisting only of vinylidene fluoride units, a fluorine-containing polymer containing vinylidene fluoride units and fluorinated monomer units (excluding vinylidene fluoride units), and vinylidene fluoride units.
  • the electrode mixture according to the eighth aspect is at least one selected from the group consisting of fluorine-containing polymers containing a fluoride unit and a unit based on the monomer (A1) represented by the general formula (A1). provided.
  • Y is an inorganic cation and/or an organic cation.
  • the binder (A) further contains a fluorine-containing copolymer containing less than 98.0 mol % of vinylidene fluoride units.
  • the fluorine-containing copolymer is a fluorine-containing copolymer containing a vinylidene fluoride unit and a fluorinated monomer unit (excluding vinylidene fluoride units), and the fluorinated monomer unit is tetrafluoroethylene.
  • the electrode mixture according to the tenth aspect which is at least one selected from the group consisting of a hexafluoropropylene unit, a fluoroalkyl vinyl ether unit, a chlorotrifluoroethylene unit, and a 2,3,3,3-tetrafluoropropene unit. is provided.
  • a hexafluoropropylene unit a fluoroalkyl vinyl ether unit
  • a chlorotrifluoroethylene unit a 2,3,3,3-tetrafluoropropene unit.
  • the electrode active material (B) contains a lithium metal oxide represented by the general formula (B1).
  • a secondary battery including an electrode according to a fourteenth aspect is provided.
  • the content of acrylic acid units in the fluoropolymer was measured by acid-base titration of carboxyl groups. Specifically, about 0.5 g of a fluoropolymer was dissolved in acetone at a temperature of 70 to 80°C. 5 ml of water was added dropwise under vigorous stirring to avoid coagulation of the fluoropolymer. A titration with an aqueous NaOH solution having a concentration of 0.1 N was carried out until complete neutralization of the acidity, with a neutral transition at approximately -270 mV. From the measurement results, the amount of acrylic acid units contained in 1 g of the fluoropolymer was determined, and the content of acrylic acid units was calculated.
  • Weight average molecular weight Measured by gel permeation chromatography (GPC). Based on the data (reference: polystyrene) measured using Tosoh's HLC-8320GPC and column (3 SuperAWM-H connected in series) and flowing dimethylformamide (DMF) as a solvent at a flow rate of 0.3 ml/min. The weight average molecular weight was calculated.
  • viscosity The viscosity of the positive electrode mixture was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., TV-10M) at a temperature of 25°C, a humidity of 0.2%, and a rotor no. Measurement was performed under the conditions of M4 and rotational speed of 6 rpm, and the value measured 10 minutes after the start of the measurement was taken as the viscosity.
  • test piece of 1.2 cm x 7.0 cm was prepared by cutting out the positive electrode. After fixing the positive electrode material layer side of the test piece to a movable jig with double-sided tape, the tape was applied to the surface of the positive electrode current collector, and the stress (N/ cm) was measured using an autograph. 50N was used for the Autograph load cell.
  • Positive electrode active material B
  • NMC811 LiNi 0.8 Mn 0.1 Co 0.1 O 2
  • Additive C
  • Tartaric acid Polyacrylic acid PAA
  • Conductive agent carbon black SuperP Li, manufactured by Imerys
  • Binder (A) was dissolved in N-methyl-2-pyrrolidone (NMP) to prepare a solution of binder (A) with a concentration of 8% by mass.
  • NMP N-methyl-2-pyrrolidone
  • a solution of the binder (A), a positive electrode active material (B), an additive (C), and a conductive agent were mixed to prepare a positive electrode mixture.
  • Tables 1 and 2 show the amount of each component used and the solid content concentration of the positive electrode mixture. The viscosity of the obtained positive electrode mixture was measured, and the viscosity change rate was calculated. The results are shown in Tables 1 and 2.
  • the obtained positive electrode mixture was uniformly applied to one side of a positive electrode current collector (aluminum foil with a thickness of 20 ⁇ m), and the NMP was completely volatilized by drying at 120°C for 60 minutes.
  • a positive electrode including a positive electrode material layer on one side of the positive electrode current collector was produced by pressing with a pressure of 10 t.
  • the coating amount of the positive electrode mixture was 22.5 mg/cm 2 , and the density of the positive electrode material layer was 3.4 g/cm 2 .
  • the peel strength between the positive electrode material layer of the positive electrode and the positive electrode current collector was measured. The results are shown in Tables 1 and 2.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

L'invention concerne un mélange d'électrode qui contient un liant (A), un matériau actif d'électrode (B) et un additif (C). Le liant (A) contient un polymère contenant du fluor qui comprend une unité de fluorure de vinylidène. L'additif (C) contient un acide polycarboxylique (C1) et un polymère exempt de fluor (C2) qui comprend une unité d'acide monocarboxylique insaturé.
PCT/JP2023/026252 2022-07-26 2023-07-18 Mélange d'électrode, électrode et batterie secondaire WO2024024568A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10255808A (ja) * 1997-03-14 1998-09-25 Kureha Chem Ind Co Ltd 電池用バインダー溶液およびその製造方法
JP2012142311A (ja) * 2010-07-16 2012-07-26 Nippon Shokubai Co Ltd 二次電池用水系電極バインダー
JP2017054822A (ja) * 2011-10-28 2017-03-16 旭化成株式会社 非水系二次電池
WO2018092675A1 (fr) * 2016-11-15 2018-05-24 株式会社クレハ Copolymère de fluorure de vinylidène, composition de liant, mélange pour électrodes, électrode, et accumulateur à électrolyte non aqueux
JP2019200895A (ja) * 2018-05-15 2019-11-21 株式会社クレハ 電極合剤、電極合剤の製造方法、電極構造体、電極構造体の製造方法および二次電池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10255808A (ja) * 1997-03-14 1998-09-25 Kureha Chem Ind Co Ltd 電池用バインダー溶液およびその製造方法
JP2012142311A (ja) * 2010-07-16 2012-07-26 Nippon Shokubai Co Ltd 二次電池用水系電極バインダー
JP2017054822A (ja) * 2011-10-28 2017-03-16 旭化成株式会社 非水系二次電池
WO2018092675A1 (fr) * 2016-11-15 2018-05-24 株式会社クレハ Copolymère de fluorure de vinylidène, composition de liant, mélange pour électrodes, électrode, et accumulateur à électrolyte non aqueux
JP2019200895A (ja) * 2018-05-15 2019-11-21 株式会社クレハ 電極合剤、電極合剤の製造方法、電極構造体、電極構造体の製造方法および二次電池

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